Hi Kevin, Tony, Paul and other experts. Woodruff, Richard wrote: >> From: Paul Walmsley [mailto:paul@xxxxxxxxx] Sent: Thursday, April >> 23, 2009 3:53 AM To: Woodruff, Richard > >>> 4. Current PM code didn't enable the maximum clock (i.e. CPU: >>> 600Mhz) according to the comment as below: >>> >>> /* Avoid registering the 120% Overdrive with CPUFreq */ prcm = >>> mpu_opps + MAX_VDD1_OPP - 1; >>> >>> But in some cases, we should use 600Mhz for multimedia >>> application. And, even thought we enable the maximum clock, CPU >>> frequency seldom goes into maximum clock. I think we don't have >>> to avoid registering the max OPP. >> Do you know if this restriction can be lifted now, i.e., can the >> silicon run at VDD1 OPP1 100% of the time and meet the device >> lifespan targets? > > So, there have been some characterization changes which give more > leeway for software usage off overdrive. > > What you found before was guarantees against typical mobile usage for > a few classes of devices. This was done using a mix of OPPs with the > majority of active time in lower OPPs and inactive time in low idles > (optimal usage for mix of typical operations, this is the way you > would want to run ideally). Against this and many more variables, > reliability data was validated and published. > > Recently there was some change to also measure active time at max > overdrive for same usage mix. This resulted in still meeting lifetime > goals for typical usage. > > This can translate to a smart phone maker of being able to use > overdrive as they see fit and still have long life (assuming they can > supply adequate power and still dissipate what ever additional heat > there is). This is still not 100% of the time in active mode. What do you think of enabling to register the 120% Overdrive with CPUFreq in l-o tree?. Regard, Kyuwon > I suspect TI will continue to create parts for certain markets when > the need is there. The part might be nearly identical but the way > it's rated (with chip binning and other tricks) will allow different > guarantees. This fits well with mobile business customer needs. > > As an open source individual owner of a device, you might do things > in a non-typical way. You are free to do this. Depending on which > base chip variant you are using, its life may have some impact (or > not). Your chip likely will still last many years. The phone or other > device might die first. > > All that said, today personally, I feel much more comfortable > exposing overdrives in the reference code. Mobile users and their > devices which actually sleep at night should be pretty safe. > > Watch data sheets for details :) > > Regards, Richard W. > -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
